1. Field of the Invention
This invention relates to the field of magnetic recording and more particularly to an improved article of manufacture for cleaning the reading and writing transducers of floppy disk drives.
2. Description of the Prior Art
Widely used in the computer industry is a removable and interchangeable data storage medium assembled by sealing an annular-shaped disk of flexible material coated with magnetic particles within a square-shaped envelope. These assemblies are known in the trade as "floppy disks". A method of constructing floppy disk assemblies is described in U.S. Pat. No. 3,668,658 issued to Flores, et al. The envelope, as described in that patent, is formed with a circular aperture passing through the centers of its side surfaces. As further taught in that patent, the diameter of the circular aperture formed through the envelope is larger than that formed through the flexible recording disk. A larger aperture is formed in the envelope to permit engagement of the recording disk contained therein by a drive spindle of an apparatus used to write data to and read data from the flexible disk. Engagement of the flexible recording disk by the drive spindle is necessary to permit rotation of the disk within the envelope by the reading and writing apparatus so that all the storage area of the circular data tracks thereof may be accessed.
The envelopes of a floppy disk assembly are further formed with a radially positioned oblong aperture. This aperture permits the reading and writing transducer of a floppy disk drive to interact with the recording surface coated on the circular disk for recording or reproducing information thereon. Some floppy disk assemblies, known as "single sided floppy disks," are fabricated with such an oblong aperture formed through only one of the side surfaces of the envelope. Other floppy disk assemblies, known as "dual sided floppy disks," are fabricated with oblong apertures passing through both side surfaces of the envelope. Correspondingly, floppy disk drives are of two types respectively adapted to read data from and write data on floppy disk assemblies of these respective types. During such reading and/or writing operations, the reading and writing transducer of a floppy disk drive, regardless of type, is inserted through the oblong aperture in the envelope and enters into intimate contact with the recording surface of the flexible disk. In the case of dual sided floppy disk drives, the reading and writing transducers and the corresponding oblong apertures in the envelope of a floppy disk are arranged so as to oppose each other from opposite sides of the flexible recording disk. Thus, a dual sided flexible recording disk is gently clamped between opposing reading and writing transducers while information is being recorded thereon or recovered therefrom. In a similar fashion, a single sided floppy disk drive includes a member, generally made from felt, which opposes the reading and writing transducer and which contacts the outer surface of the envelope during reading and writing operations.
Because the floppy disk assembly may be removed from the floppy disk drive, these drives are constructed so that the reading and writing transducer contacts the flexible recording disk only when a floppy disk assembly is inserted therein, has been engaged by the spindle thereof, and is rotating. To permit sensing the rotation of the flexible recording disk, these assemblies generally include a circular aperture passing through the envelope with which a smaller circular aperture in the flexible recording disk may be aligned. The floppy disk drive then employs a light source and an optical sensor aligned with the aperture through the inserted envelope to sense the periodic alignment of the apertures as the flexible recording disk rotates. If a floppy disk drive does not sense the rotation of the flexible recording disk even though one be inserted, it will not attempt to move the reading and writing transducers into contact with the recording surface thereof.
The magnetic recording layer coated onto the annular-shaped sheet of flexible material generally comprises small particles of magnetic material and a lubricant dispersed throughout a binder material which adheres to the flexible sheet material. It is this coating which the reading and writing transducers of a floppy disk drive contact as data is stored on or recovered from the floppy disk assembly. In time, due to the intimate contact between these elements of the floppy disk drive and the floppy disk assembly, the transducers become contaminated with material abraded from the surface of the flexible recording disk. Left unattended, this contamination can become so severe as to prevent the proper recording and/or reading of data. Therefore, it has been found beneficial to periodically clean the surface of the reading and writing transducers to remove this contamination therefrom.
Methods of construction and the use of articles of manufacture to facilitate this cleaning of the reading and writing transducers of floppy disk drives have been disclosed in U.S. Pat. No. 4,065,798, issued to Sugisaki et al. and U.S. Pat. No. 4,106,067 issued to Masuyama et al. Both Sugisaki and Masuyama disclose a cleaning disk assembly, open along one edge, into which is inserted a circular disk of flexible head cleaning material. The circular cleaning disks of both the Sugisaki and Masuyama patents comprise a layer of non-magnetic support sheet material, analagous to the sheet material of the flexible recording disk. One surface of this sheet is coated with a magnetic layer in the case of Sugisaki or an antistatic layer in the case of Masuyama. The other surface of this sheet is coated with a fibrous material layer in both patents. The envelopes of both the Sugisaki and Masuyama patents further include a layer of lubricating material secured to the inner side surface of the envelope opposite to that contacted by the fibrous cleaning layer.
Currently, cleaning disk assemblies having a much simplier structure than that taught by Sugisaki and Masuyama are commercially available. These simpler cleaning disk assemblies employ only a circular disk of cleaning material formed from a sheet of spun-bonded fibrous material such as Reemay polyester fabric manufactured by Du Pont De Nemours E I & Company. However, these cleaning disks consisting solely of the fibrous material are permanently sealed into an envelope such as that normally used to enclose the flexible recording disks. Permanently sealed envelopes are used to contain the commercially available fibrous cleaning disks in order to prevent creasing them. The additional mechanical rigidity of a sealed envelope, not required for the cleaning disk assemblies taught by Sugisaki and Masuyama, is required for the soft fibrous cleaning disks because they do not supplement the mechanical rigidity of the envelope with the additional strength of the nonmagnetic material layer to which Sugisaki and Masuyama secure the fibrous cleaning layer. Creasing of the fibrous cleaning disk causes the reading and writing transducers to bounce as the crease in the rotating disk passes them.
These cleaning disk assemblies employing only a layer of fibrous material may be separated into two categories, i.e., those having dry cleaning material and those having wet cleaning material. Those having dry cleaning material remove contamination from the reading and writing transducer by abrasion and physical entrapment of the contamination within the fibrous material of the cleaning disk. In order to assure proper operation of the floppy disk drive upon insertion of the cleaning disk therein, the dry cleaning disks are fabricated with an opaque piece of material adhesively bonded to the surface of the fibrous material about the aperture formed therethrough for sensing by the disk drive. The opaque material increases the optical density of the cleaning disk about the aperture so that the optical sensor incorporated into the floppy disk drive will provide a reliable signal.
The wet cleaning disk assemblies are of a generally similar construction to that of the dry cleaning assemblies with the major difference being that immediately prior to their use the material of the cleaning disk is satured with a cleaning solution. However, the wet cleaning disk assemblies currently cannot employ the adhesively bonded opaque material because the cleaning solution dissolves the adhesive. The lack of opaque material about the sensing aperture causes the presence of the wet cleaning disk assembly within the floppy disk drive to be sensed approximately one time out of five that the assemblies are inserted therein. Thus, on the average, a wet cleaning disk assembly must be inserted and removed from a floppy disk drive five times before the drive will sense its presence thereby permitting the reading and writing transducers to contact it and be cleaned. Another problem with the currently available wet cleaning disk assemblies is that the envelopes thus far used are fabricated from polyvinyl chloride. This material is generally subject to chemical attach and the cleaning solutions thus bleed monomers from the envelope material that may contaminate the floppy disk drive apparatus.
Because both the dry and wet cleaning disks are permanently sealed within an envelope, their cleaning effectiveness decreases with repetitive use which ultimately requires disposal of the entire cleaning disk assembly. Furthermore, the presence of cleaning solution saturated wet cleaning disk assemblies saved for future use creates a fire hazard because the solutions are generally compounded from combustible hydrocarbons.
Lastly, the commercially available dry and wet cleaning disk assemblies must be irreversible committed to use in a dual sided floppy disk drive because the envelopes incorporate a perforated pull-out tab which must be removed prior to use in dual sided drives. Removal of this pull-out tab renders the cleaning disk assembly unsuitable for use in a single sided drive because the felt surface opposing the head thereof will be damaged by contacting the rotating surface of the cleaning disk.